Memory data randomizer

ABSTRACT

A method is provided of initializing a chip having synaptic NVRAM cells connected row-wise by word lines and column-wise by bit lines. The method includes selecting each word line through a row decoder connected to all word lines to switch all synaptic NVRAM cells of the selected lines. The method includes driving, on the selected lines, a wave generated by a PLL circuit connected to the row decoder. The method includes generating standing waves from the wave on the selected lines by implementing a resonance detection point at an input end of each word line. The method includes applying a write voltage on all bit lines through a column decoder connected to all bit lines. The method includes simultaneously driving each of the synaptic NVRAM cells of the selected lines by different writing currents for different durations in order to set different analog values to the synaptic NVRAM cells.

BACKGROUND Technical Field

The present invention relates generally to memory devices and, inparticular, to a memory data randomizer.

Description of the Related Art

Non-Volatile Random Access Memory (NVRAM) is used as an analog memorydevice for cognitive systems. To obtain stochastic behaviors in neuralnetworks, it is desirable to add a random offset to data. Accordingly,cells of a NVRAM should have random values on a reset. Hence, there is aneed for a memory data randomizer capable of adding random values tocells of a NVRAM on a reset.

SUMMARY

According to an aspect of the present invention, a method is provided ofinitializing a chip having synaptic Non-Volatile Random Access Memory(NVRAM) cells connected row-wise by word lines and column-wise by bitlines. The method includes selecting each of the word lines through arow decoder connected to all of the word lines to switch all of thesynaptic NVRAM cells of the selected word lines. The method furtherincludes driving, on the selected word lines, a wave generated by aPhase Locked Loop (PLL) circuit connected to the row decoder. The methodalso includes generating standing waves from the wave on the selectedword lines by implementing a resonance detection point at an input endof each the word lines. The method additionally includes applying awrite voltage on all of the bit lines through a column decoder connectedto all of the bit lines. The method further includes simultaneouslydriving each of the synaptic NVRAM cells of the selected word lines bydifferent writing currents for different durations in order to setdifferent analog values to all of the synaptic NVRAM cells.

According to another aspect of the present invention, a computer programproduct is provided for initializing a chip having synaptic Non-VolatileRandom Access Memory (NVRAM) cells connected row-wise by word lines andcolumn-wise by bit lines. The computer program product includes anon-transitory computer readable storage medium having programinstructions embodied therewith. The program instructions are executableby a computer to cause the computer to perform a method. The methodincludes selecting each of the word lines through a row decoderconnected to all of the word lines to switch all of the synaptic NVRAMcells of the selected word lines. The method further includes driving,on the selected word lines, a wave generated by a Phase Locked Loop(PLL) circuit connected to the row decoder. The method also includesgenerating standing waves from the wave on the selected word lines byimplementing a resonance detection point at an input end of each theword lines. The method additionally includes applying a write voltage onall of the bit lines through a column decoder connected to all of thebit lines. The method further includes simultaneously driving each ofthe synaptic NVRAM cells of the selected word lines by different writingcurrents for different durations in order to set different analog valuesto all of the synaptic NVRAM cells.

According to yet another aspect of the present invention, a system isprovided for initializing a chip having synaptic Non-Volatile RandomAccess Memory (NVRAM) cells connected row-wise by word lines andcolumn-wise by bit lines. The system includes a column decoder connectedto all of the bit lines. The system further includes a row decoder,connected to all of the word lines, for selecting each of the word linesto switch all of the synaptic NVRAM cells of the selected word lines.The system also includes a Phase Locked Loop (PLL) circuit connected tothe row decoder for driving a wave on the selected word lines. Thesystem additionally includes a resonance detection point implemented atan input end of each the word lines to generate standing waves from thewave on the selected word lines. The system further includes a switchfor applying a write voltage on all of the bit lines through the columndecoder, Each of the synaptic NVRAM cells of the selected word lines issimultaneously driven by different writing currents for differentdurations in order to set different analog values to all of the synapticNVRAM cells.

These and other features and advantages will become apparent from thefollowing detailed description of illustrative embodiments thereof,which is to be read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description will provide details of preferred embodimentswith reference to the following figures wherein:

FIG. 1 shows an exemplary processing system to which the presentinvention may be applied, in accordance with an embodiment of thepresent invention;

FIG. 2 shows an exemplary simplified NVRAM architecture to which thepresent invention can be applied, in accordance with an embodiment ofthe present invention;

FIG. 3 shows a memory device to which the present invention can beapplied, in a resonance calibration mode, in accordance with anembodiment of the present invention;

FIG. 4 shows a memory device to which the present invention can beapplied, in a cell initialization mode, in accordance with an embodimentof the present invention;

FIG. 5 shows a memory device to which the present invention can beapplied, in a random offset mode, in accordance with an embodiment ofthe present invention;

FIG. 6 shows a memory device to which the present invention can beapplied, using a bias generator, in accordance with an embodiment of thepresent invention;

FIG. 7 shows an exemplary method for memory data randomization, inaccordance with an embodiment of the present invention; and

FIG. 8 shows various resonance modes, in accordance with an embodimentof the present invention.

DETAILED DESCRIPTION

The present invention is directed to a memory data randomizer.

In an embodiment, the present invention provides a hardware scheme that(1) adds random offset to the data and (2) quickly initializes NVRAMcells with different values.

In an embodiment, the present invention can drive a word line by ahigh-frequency wave. In an embodiment, the present invention can make astanding wave on the word line. In an embodiment, the present inventioncan drive multiple cells by different currents for a different period oftime in order to set different values to each cell. These and otherfeatures of the present invention will be described in further detailherein below.

FIG. 1 shows an exemplary processing system 100 to which the inventionprinciples may be applied, in accordance with an embodiment of thepresent invention. The processing system 100 includes at least oneprocessor (CPU) 104 operatively coupled to other components via a systembus 102. A cache 106, a Read Only Memory (ROM) 108, a Random AccessMemory (RAM) 110, an input/output (I/O) adapter 120, a sound adapter130, a network adapter 140, a user interface adapter 150, and a displayadapter 160, are operatively coupled to the system bus 102. At least oneGraphics Processing Unit (GPU) 194 is operatively coupled to the systembus 102.

A first storage device 122 and a second storage device 124 areoperatively coupled to system bus 102 by the I/O adapter 120. Thestorage devices 122 and 124 can be any of a disk storage device (e.g., amagnetic or optical disk storage device), a solid state magnetic device,and so forth. The storage devices 122 and 124 can be the same type ofstorage device or different types of storage devices.

A speaker 132 is operatively coupled to system bus 102 by the soundadapter 130. A transceiver 142 is operatively coupled to system bus 102by network adapter 140. A display device 162 is operatively coupled tosystem bus 102 by display adapter 160.

A first user input device 152, a second user input device 154, and athird user input device 156 are operatively coupled to system bus 102 byuser interface adapter 150. The user input devices 152, 154, and 156 canbe any of a keyboard, a mouse, a keypad, an image capture device, amotion sensing device, a microphone, a device incorporating thefunctionality of at least two of the preceding devices, and so forth. Ofcourse, other types of input devices can also be used, while maintainingthe spirit of the present invention. The user input devices 152, 154,and 156 can be the same type of user input device or different types ofuser input devices. The user input devices 152, 154, and 156 are used toinput and output information to and from system 100.

Of course, the processing system 100 may also include other elements(not shown), as readily contemplated by one of skill in the art, as wellas omit certain elements. For example, various other input devicesand/or output devices can be included in processing system 100,depending upon the particular implementation of the same, as readilyunderstood by one of ordinary skill in the art. For example, varioustypes of wireless and/or wired input and/or output devices can be used.Moreover, additional processors, controllers, memories, and so forth, invarious configurations can also be utilized as readily appreciated byone of ordinary skill in the art. These and other variations of theprocessing system 100 are readily contemplated by one of ordinary skillin the art given the teachings of the present invention provided herein.

FIG. 2 shows an exemplary simplified NVRAM architecture 200 to which thepresent invention can be applied, in accordance with an embodiment ofthe present invention.

The NVRAM architecture 200 includes a row decoder 201, a column decoder202, a first row of N-channel enhancement mode Metal Oxide SemiconductorField Effect Transistors (MOSFETs) 221, a second row of N-channelenhancement mode MOSFETs 222, an N-channel enhancement mode MOSFET 291and an N-channel enhancement mode MOSFET 292. The NVRAM architecturefurther includes word lines 231 and bit lines 232.

The MOSFET 291 is used to control the row decoder 201, and the MOSFET292 is used to control the column decoder 202, where such control caninvolve row and column selection, respectively.

It is to be appreciated that the use of a memory architecture having tworows and four columns as shown in the NVRAM architecture 200 of FIG. 2is merely illustrative and that other embodiments of the presentinvention can involve memory architectures having other numbers of rowsand columns. It is to be further appreciated that the present inventioncan be applied to others memory architectures and configurations. Theseand other variations of a memory device to which the present inventioncan be applied are readily determined by one of ordinary skill in theart, given the teachings of the present invention provided herein, whilemaintaining the spirit of the present invention.

Various modes of a memory device being used in accordance with theteachings of one or more embodiments of the present invention will bedescribed hereinafter with respect to FIGS. 3-6, with such memory deviceinvolving a similar architecture to that shown and described withrespect to FIG. 2 for the sake of illustration. The memory device inFIGS. 3-6 can be the same memory device, with different elements andconnections applicable and shown depending upon the current mode appliedto the memory device, as readily appreciated by one of ordinary skill inthe art. For example, in the case of FIG. 6, additional bias elementscan be added or involved in the memory device in order to provide thebias described with respect to FIG. 6.

While one or more embodiments of the present invention are shown anddescribed with respect to N-channel enhancement mode MOSFETs, thepresent invention is not limited to the same. Thus, other embodiments ofthe present invention can use other types of transistors, as readilyappreciated by one of ordinary skill in the art, while maintaining thespirit of the present invention.

In an embodiment, the memory device can be implemented in a chip (e.g.,an Application Specific Integrated Circuit (ASIC), a three-dimension(3D) chip stack, and so forth). In an embodiment, the chip can be aneuromorphic chip. In an embodiment, the neurotrophic chip can havemultiple synaptic Non-Volatile Random Access Memory (NVRAM) cells. In anembodiment, the cells can be interconnected row-wise by word-lines andcolumn-wise by bit-lines (or vice-versa) to form a neuromorphic chip asa synaptic cell array. These and other types of chips and/or cellarrangements can also be used, while maintaining the spirit of thepresent invention.

FIG. 3 shows a memory device 300 to which the present invention can beapplied, in a resonance calibration mode, in accordance with anembodiment of the present invention.

In the resonance calibration mode, the memory device 300 involves a rowdecoder 201, a column decoder with broadcast capability 302, a first rowof N-channel enhancement mode Field Effect Transistors (MOSFETs) 221, asecond row of N-channel enhancement mode MOSFETs 222, avoltage-controlled crystal oscillator VXCO 303, a phase detector 304, aLow Pass Filter (LPF) 305, a Voltage Controlled Oscillator (VCO) 306, afrequency divider/multiplier 307, a resonance controller 308, a Low PassFilter (LPF) 309, a multiplexer 310, a switch SW_V 311, and a resonancedetection point 350 (at each row decoder end of each word line, that is,the end of each word line closest to the row decoder). The memory device300 further involves word lines 231 and bit lines 232. The word lines231 are connected to gates of the MOSFETs 221 and 222, and the bit linesare connected to the drains of the MOSFETs 221 and 222.

It is to be appreciated that the phase detector 304, the LPF 305, andthe VCO 306 can be considered to form a Phase Locked Loop (PLL) circuit366, such that the phase of the output of the VCO 306 is related to thephase of the input to the phase detector 304.

In the resonance calibration mode, the resonance controller 308 is usedto control the frequency (by controlling the frequencydivider/multiplier 307) so as to minimize the voltage at the resonancedetection point 350 (which is modified by the standing wave 391). Tothat end, the VXCO driving voltage and frequency divider/multipliervalues for each word are memorized.

In an embodiment, the row decoder 201 can be configured to drive one ormore word lines in parallel.

FIG. 4 shows a memory device 400 to which the present invention can beapplied, in a cell initialization mode, in accordance with an embodimentof the present invention.

In the cell initialization mode, the memory device 400 involves a rowdecoder 201, a column decoder with broadcast capability 302, a first rowof N-channel enhancement mode Field Effect Transistors (MOSFETs) 221, asecond row of N-channel enhancement mode MOSFETs 222, avoltage-controlled crystal oscillator VXCO 303, a phase detector 304, aLow Pass Filter (LPF) 305, a Voltage Controlled Oscillator (VCO) 306, afrequency divider/multiplier 307, a resonance controller 308, a Low PassFilter (LPF) 309, a multiplexer 310, a switch SW_V 311, a switch SW_W412, a set of Pulse Width Modulators (PWMs) 440, and a resonancedetection point 350 (at each row decoder end of each word line, that is,the end of each word line closest to the row decoder). The memory device300 further involves word lines 231 and bit lines 232.

In an embodiment, the row decoder 201 can be configured to drive one ormore word lines in parallel.

The set of Pulse Width Modulators (PWMs) 440 are connected to the columndecoder 302 to further randomize the writing current.

In the cell initialization mode, the standing waves 391 and 392(generated by the PLL 366) are used, in conjunction with the set of PWMs440 to initialize each of memory cells (represented by the sets ofMOSFETs 221 and 222) with different values.

FIG. 5 shows a memory device 500 to which the present invention can beapplied, in a random offset mode, in accordance with an embodiment ofthe present invention.

In the random offset mode, the memory device 500 involves a row decoder201, a column decoder with broadcast capability 302, a first row ofN-channel enhancement mode Field Effect Transistors (MOSFETs) 221, asecond row of N-channel enhancement mode MOSFETs 222, avoltage-controlled crystal oscillator VXCO 303, a phase detector 304, aLow Pass Filter (LPF) 305, a Voltage Controlled Oscillator (VCO) 306, afrequency divider/multiplier 307, a resonance controller 308, a Low PassFilter (LPF) 309, a switch SW_V 311, a capacitor 513, a capacitor 514,and a wave driving point 560. The memory device 300 further involvesword lines 231 and bit lines 232.

In the random offset mode, the standing waves 391 and 392 (generated bythe PLL 366) are used to initialize each of memory cells (represented bythe sets of MOSFETs 221 and 222) with a random offset.

FIG. 6 shows a memory device 600 to which the present invention can beapplied, using a bias generator, in accordance with an embodiment of thepresent invention.

The memory device 600 involves a row decoder 201, a column decoder withbroadcast capability 302, a first row of Field Effect Transistors(MOSFETs) 221, a second row of MOSFETs 222, a voltage-controlled crystaloscillator VXCO 303, a phase detector 304, a Low Pass Filter (LPF) 305,a Voltage Controlled Oscillator (VCO) 306, a frequencydivider/multiplier 307, a resonance controller 308, a Low Pass Filter(LPF) 309, a multiplexer 310, a switch SW_V 311, a switch SW_W 412, aset of Pulse Width Modulators (PWMs) 440, a resonance detection point350 (at each row decoder end of each word line, that is, the end of eachword line closest to the row decoder), a bias generator 660. The biasgenerator 660 includes a switch 661, a bias element 662, a switch 663,and a bias element 664. The bias elements can be a cell(s), acapacitor(s), a transistor(s), and so forth. The memory device 300further involves word lines 231 and bit lines 232.

The bias generator 660 adds a bias to the word lines 231 such that thenodes connected thereto can have a non-zero voltage.

FIG. 7 shows an exemplary method 700 for memory data randomization, inaccordance with an embodiment of the present invention.

At step 710, select each of the word lines through a row decoderconnected to all of the word lines to switch all of the synaptic NVRAMcells of the selected word lines.

At step 720, drive, on the selected word lines, a high frequency wave(e.g., up to 100 GHz, although other (e.g., higher values can also beused) generated by a Phase Locked Loop (PLL) circuit connected to therow decoder.

At step 730, generate standing waves from the high frequency wave on theselected word lines by implementing a resonance detection point to aninput end (the row detector side) of each the word lines.

At step 740, apply a write voltage (V_(A)) on all of the bit linesthrough a column decoder connected to all of the bit lines.

At step 750, simultaneously drive each of the synaptic NVRAM cells ofthe selected word-lines by different writing currents for differentdurations in order to set different analog values to all of the synapticNVRAM cells.

In an embodiment, step 750 can include one or more of steps 750A and750B.

At step 750A, apply a set of Pulse Width Modulators (PWMs) to each ofthe bit lines to further randomize the different writing currents.

At step 750, apply a bias to each of the word lines. In this way, thenode can have a non-zero voltage.

FIG. 8 shows various resonance modes 800, in accordance with anembodiment of the present invention.

The resonance modes 800 include resonance modes 810 involving a lowimpedance driver 821 and resonance modes 850 involving a high impedancedriver 861.

Regarding the various resonance modes 800 are based on an assumption ofa 2 mm word line and a relative dielectric constant of 3.

The lowest resonance frequency is 300÷2÷4÷√{square root over (3)}=21GHz.

The resonance modes 810 involving the low impedance driver 821 include a¼λ resonance mode 811, a ¾λ resonance mode 812, and a 5/4λ resonancemode 813. As is known, the symbol “λ” denotes wavelength.

The resonance modes 850 involving the high impedance driver 861 includea ½λ resonance mode 851, a 1λ resonance mode 852, and a 3/2λ resonancemode 853.

The present invention may be a system, a method, and/or a computerprogram product at any possible technical detail level of integration.The computer program product may include a computer readable storagemedium (or media) having computer readable program instructions thereonfor causing a processor to carry out aspects of the present invention.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as SMALLTALK, C++ or the like, andconventional procedural programming languages, such as the “C”programming language or similar programming languages. The computerreadable program instructions may execute entirely on the user'scomputer, partly on the user's computer, as a stand-alone softwarepackage, partly on the user's computer and partly on a remote computeror entirely on the remote computer or server. In the latter scenario,the remote computer may be connected to the user's computer through anytype of network, including a local area network (LAN) or a wide areanetwork (WAN), or the connection may be made to an external computer(for example, through the Internet using an Internet Service Provider).In some embodiments, electronic circuitry including, for example,programmable logic circuitry, field-programmable gate arrays (FPGA), orprogrammable logic arrays (PLA) may execute the computer readableprogram instructions by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

Reference in the specification to “one embodiment” or “an embodiment” ofthe present invention, as well as other variations thereof, means that aparticular feature, structure, characteristic, and so forth described inconnection with the embodiment is included in at least one embodiment ofthe present invention. Thus, the appearances of the phrase “in oneembodiment” or “in an embodiment”, as well any other variations,appearing in various places throughout the specification are notnecessarily all referring to the same embodiment.

It is to be appreciated that the use of any of the following “/”,“and/or”, and “at least one of”, for example, in the cases of “A/B”, “Aand/or B” and “at least one of A and B”, is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of both options (A andB). As a further example, in the cases of “A, B, and/or C” and “at leastone of A, B, and C”, such phrasing is intended to encompass theselection of the first listed option (A) only, or the selection of thesecond listed option (B) only, or the selection of the third listedoption (C) only, or the selection of the first and the second listedoptions (A and B) only, or the selection of the first and third listedoptions (A and C) only, or the selection of the second and third listedoptions (B and C) only, or the selection of all three options (A and Band C). This may be extended, as readily apparent by one of ordinaryskill in this and related arts, for as many items listed.

Having described preferred embodiments of a system and method (which areintended to be illustrative and not limiting), it is noted thatmodifications and variations can be made by persons skilled in the artin light of the above teachings. It is therefore to be understood thatchanges may be made in the particular embodiments disclosed which arewithin the scope of the invention as outlined by the appended claims.Having thus described aspects of the invention, with the details andparticularity required by the patent laws, what is claimed and desiredprotected by Letters Patent is set forth in the appended claims.

1. A method of initializing a chip having synaptic Non-Volatile RandomAccess Memory (NVRAM) cells connected row-wise by word lines andcolumn-wise by bit lines, the method comprising: selecting each of theword lines through a row decoder connected to all of the word lines toswitch all of the synaptic NVRAM cells of the selected word lines;driving, on the selected word lines, a wave generated by a Phase LockedLoop (PLL) circuit connected to the row decoder; generating standingwaves from the wave on the selected word lines by implementing aresonance detection point at an input end of each the word lines;applying a write voltage on all of the bit lines through a columndecoder connected to all of the bit lines; and simultaneously drivingeach of the synaptic NVRAM cells of the selected word lines by differentwriting currents for different durations in order to set differentanalog values to all of the synaptic NVRAM cells.
 2. The method of claim1, wherein the chip is a neuromorphic chip.
 3. The method of claim 2,wherein the NVRAM cells of the neuromorphic chip are configured to forma synaptic cell array.
 4. The method of claim 1, wherein applying awrite voltage comprises closing a switch connecting the column decoderto the write voltage.
 5. The method of claim 1, further comprising usinga respective set of capacitors at the input end of the word lines toprovide a random offset to the different analog values on the selectedword-lines.
 6. The method of claim 1, wherein each of the word linescomprise the input end and an output end, the input end being closest tothe row decoder, and the output end being farthest from the row decoder.7. The method of claim 1, further comprising applying a set of PulseWidth Modulators (PWMs) to the bit lines to further randomize thedifferent writing currents.
 8. The method of claim 1, further comprisinginputting detected resonance on the resonance detection point on each ofthe selected word lines to a multiplexer for selectively providing acontrol signal to the PLL.
 9. The method of claim 1, wherein the wave isdriven by the PLL on multiple ones of the selected word lines inparallel.
 10. The method of claim 1, further comprising adding a bias tothe selected word lines. 11-19. (canceled)
 20. A system for initializinga chip having synaptic Non-Volatile Random Access Memory (NVRAM) cellsconnected row-wise by word lines and column-wise by bit lines, thesystem comprising: a column decoder connected to all of the bit lines; arow decoder, connected to all of the word lines, for selecting each ofthe word lines to switch all of the synaptic NVRAM cells of the selectedword lines; a Phase Locked Loop (PLL) circuit connected to the rowdecoder for driving a wave on the selected word lines; a resonancedetection point implemented at an input end of each the word lines togenerate standing waves from the wave on the selected word lines; and aswitch for applying a write voltage on all of the bit lines through thecolumn decoder, wherein each of the synaptic NVRAM cells of the selectedword lines is simultaneously driven by different writing currents fordifferent durations in order to set different analog values to all ofthe synaptic NVRAM cells.